Coffer-dam



2 Sheets-Sheet 1.

(No Model.)

' H. P. KIRKHAM.

COPPER DAM.

Patented June 4; 1889.

22/52 i l'l 1! r 1 i, ll.

WITNESSES:

v ATTORNEY H. PErERs. Phnto-Lilhngnpher, wamingwn. DC.

(No Model.) 2 Sheets-Sheet H. P. KIRKHAM.

COPPER DAM No. 404,718. Patented June 4, 1889 WITNESSES.

ATTORNEY N. PETERS. Pholc-Lilhogmphnr, washin mn. D. c.

UNITED STATES PATENT OFFICE.

HENRY P. KIRKIIAM, OF BROOKLYN, NEIV YORK.

COFFER-DAM.

SPECIFICATION forming part of Letters Patent No. 404,718, dated June 4, 1889.

Application filed May 15, 1888. Serial No. 273,969. (No model.)

, specification.

This invention relates to improvements in coifer-dams; and the invention consists of a cotter-dam constructed in the manner herein shown, described, and claimed.

In the accompanying sheet of drawings, Figure 1 is a plan or top view of the cofferdam; Fig. 2, a cross-section of same; Fig. 3, an end view showing gates; Fig. 4, elevation of sliding gate.

Similar letters of reference indicate like parts in the several figures.

This invention is mainly an improvement on the colfer-dam heretofore patented by me 011 the 31st of January, 1882, in Patent No. 253,067. In that patent the hinged gates are shown only on the upper sect-ion of the dam, the lower section being closed by bulk-heads. This construction answered the purpose for an ordinary steamer provided with but one screw placed in line with the keel of the ship; but since the introduction of this dam vessels with the so-called twin screws are to the sides of the dam as far as the ballast.

tanks B will permit, and then slope off the lower part of the hinged doors to correspond to the shape of the tanks. The advantage of this form of hinged door is that when the coffer-dam is used in shallow waterin which case it may rest upon the bottom of the harbor before the doorsA are closed preparatory to pumping out and floating the dam in place under the ship-there can be no danger that the closing of the doors and the subsequent operation of the dam would be seriously interfered with by the mud, &c., that might be scraped up by doors of another form in the process of closing them. This difficulty could not occur with the dam as shown in the patent above mentioned, because of the closed bulk-heads B, above which the doors were hinged; but such construction would not admit a ship with twin screws, and to adapt the dam to vessels having such screws and to prevent the doors in shallow water from scraping up the bottom, I hinge the doors to the edges a of the dam, so that I can have the largest possible opening and let their bottoms extend to and follow the form of the ballasttanks B, which practically form the sills of the doors.

The other features of the construction of my dam improved as described, not differing materially from such features patented by me as aforesaid, I need not again describe.

Having now described my invention, what I claim as new, and desire to Secure by Letters Patent, is

In a coifer-dam, the gates A, hinged to the sides of the dam and extending from the top to the bottom of the dam, said gates having oblique bottom edges, as and for the purpose described.

HENRY P. KIRKHAM.

In presence of I). A. CARPENTER, G. M. FIELD. 

